Advances in data storage technology have provided for ever-increasing storage capability in devices such as DVD-ROMs, optical drives, and disk drives. In hard disk drives, for example, the width of a written data track has decreased due in part to advances in reading, writing, and positioning technologies. More narrow data tracks result in higher density drives, which is good for the consumer but creates new challenges for drive manufacturers. As the density of the data increases, the tolerance for error in the position of a drive component such as a read/write head decreases. As the position of such a head relative to a data track becomes more important, so too does the placement of information, such as servo data, that is used to determine the position of a head relative to a data track.
One servowriting technique involves self servowriting. One class of self-servowriting techniques is know as propagation self-servowriting. In propagation self servowriting, signals from previously written servo wedges are used to determine the position of later servo wedges. In this way, the servo wedges are propagated across the disk.